In practice, in roller mills the mill platen which drives the mill rollers over the mill bed is generally driven. However, this results in powerful fluctuations in power and consequently high loads on the drive mechanism so that there are great limitations on the drive power which can safely be transmitted.
Therefore, it has already been proposed in DE 197 02 854 A1 to drive the rollers. Reference was also made therein that the individual mill rollers, on the one hand, are connected together in terms of rotational driving by means of the mill platen and the comminution material or milling material bed located thereon but, on the other hand, can have widely differing power consumptions which are attributable, for example, to different rolling diameters on the mill platen (friction point/diameter), different operational diameters of the individual mill rollers (for example, owing to wear) and different behaviour involving the intake of the comminution material in conjunction with the mill platen and mill roller.
Even small changes in speed between individual mill rollers cause relatively high power fluctuations in the individual drives. This can result in the mill rollers constantly being accelerated or slowed down, that is to say, the individually driven mill rollers function counter to each other, which results in a significantly increased requirement for power or energy during comminution operation.
Therefore, it is proposed in DE-A1-197 02 854 that the operational fluctuations between the individual rotary drives of all the driven mill rollers be compensated for by a common load compensation control operation. However, the power consumptions of the drives are very different in the case of dynamic transmission changes between the mill platen and the mill roller.
Therefore, the problem addressed by the invention is to improve the compensation control operation for the drives.